Compositions for inhibiting the formation of hydrate agglomerates

ABSTRACT

A composition comprising the following formula and optionally salts thereof is disclosed and claimed.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No.12/396,076, “Compositions Containing Amide Surfactants and Methods forInhibiting the Formation of Hydrate Agglomerates,” filed on Mar. 2,2009, now U.S. Pat. No. 8,288,323.

FIELD OF THE INVENTION

This invention pertains to one or more compositions and methods forinhibiting the formation of hydrate agglomerates in a fluid comprisingwater, gas, and optionally liquid hydrocarbon, e.g. a fluid in an oil orgas pipeline or refinery.

BACKGROUND OF THE INVENTION

Since Hammerschmidt discovered in 1934 that gas hydrates block gaspipelines, research for the prevention of hydrate formation andagglomeration has become an important matter. Gas hydrates can be easilyformed during the transportation of oil and gas in pipelines when theappropriate conditions are present. Water content, low temperatures, andelevated pressure are required for the formation of gas hydrates. Theformation of gas hydrates often results in lost oil production, pipelinedamage, and safety hazards to field workers.

There are two approaches to prevent or slowdown the formation of gashydrates, thermodynamic inhibitors and low dosage hydrate inhibitors(LDHIs). Thermodynamic inhibitors are substances that can reduce thetemperature at which the hydrates form at a given pressure and watercontent. Methanol and ethylene glycol are among the most commonthermodynamic inhibitors used in the oil industry. Althoughthermodynamic inhibitors are quite effective, they require large dosesto achieve high concentration in the water phase. Thermodynamicinhibitors are regularly dosed at concentrations as high as 50% based onwater content during oil and gas production. Therefore, there is asubstantial cost associated with the transportation and storage of largequantities of these solvents. A more cost-effective alternative is theuse of LDHIs, as they generally require less than a 2% dose based onwater content to inhibit the nucleation or growth of gas hydrates. Thereare two general types of LDHI, kinetic hydrate inhibitors (KHIs) andanti-agglomerants (AAs/AA). KHIs work by delaying the growth of gashydrate crystals as anti-nucleators. AAs allow the hydrates to form butthen prevent them from agglomerating and accumulating into larger massescapable of causing plugs in oil and gas pipelines. An AA enables gashydrates to form but in the shape of a fluid slurry dispersed in theliquid hydrocarbon phase. In general, the water cut should be below 50%because otherwise the slurry becomes too viscous to transport.

There is an ongoing need for new and effective methods of inhibiting theformation of hydrate agglomerates, particularly those that are capableof operating under higher water-cuts.

SUMMARY OF THE INVENTION

The invention pertains to compositions, e.g. anti-agglomerants, as wellas methods for inhibiting the formation of hydrate agglomerates in afluid comprising water, gas, and optionally liquid hydrocarbon.

In one aspect, the present invention provides for a compositioncomprising the following formula and optionally salts thereof:

where R₁ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; or H;where R₂ is a C₄ to C₂₂ alkyl;where R₃ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; or H;where R₄ is C_(n)H_(2n+1), wherein n=0 to 22; or Hwhere X⁻ is an anion, halogen, a carboxylate, or a sulfate and whereinX⁻ is only present when both R₁ and R₃ are present;where Y=(CH₂)_(n), wherein n=1 to 8; andwherein R₃ and R₁ can not be hydrogen or n=0 at the same time.

In another aspect, the present invention provides for a method ofinhibiting the formation of hydrate agglomerates in a fluid comprisingwater, gas, and optionally liquid hydrocarbon comprising adding to thefluid an effective amount of a composition comprising the followingformula and optionally salts thereof:

where R₁ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; or H;where R₂ is a C₄-C₂₂ alkyl;where R₃ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; or H;where R₄ is C_(n)H_(2n+1), wherein n=0 to 22; or Hwhere X⁻ is an anion, halogen, a carboxylate, or a sulfate and whereinX⁻ is only present when both R₁ and R₃ are present;where Y=(CH₂)_(n), wherein n=1 to 8; andwherein R₃ and R₁ can not be hydrogen or n=0 at the same time.

DETAILED DESCRIPTION OF THE INVENTION A. Compositions

As stated above, the compositions contain a generic formula.

In one embodiment, the compositions contain various amounts of differentcompositions that fall within the claimed formula.

In another embodiment, the alkyl groups of R₁ and/or R₂ and/or R₄ arelinear, branched, cyclic, and/or unsaturated.

In another embodiment, R₃ is a methyl or ethyl group. When possible thealkyl groups can be linear or branched.

In another embodiment, the halogen is chlorine, bromine, or iodine. Thehalogen is in ionic form when it is associated with the composition.

In another embodiment, Y=(CH₂)_(n), wherein n=1 to 4. When possible, Yis linear or branched.

In another embodiment, R₁ is a C₄-C₈ alkyl.

In another embodiment, R₂ is a C₆-C₁₈ alkyl.

In another embodiment, the composition contains the following formulaand optionally salts thereof:

where R₁ is C₄H₉, C₆H₁₃, C₈H₁₇, or benzyl;

where R₂ is a C₈H₁₇, C₁₂H₂₅, or C₁₈H₃₅;

where R₃ is CH₃ or C₂H₅;

where R₄ is C_(n)H_(2n+1), wherein n=0 to 22; or H

where X⁻ is an anion, halogen, a carboxylate, or a sulfate and whereinX⁻ is only present when both R₁ and R₃ are present;

where Y=(CH₂)_(n), wherein n=1 to 8; and

wherein R₃ and R₁ can not be hydrogen or n=0 at the same time.

In a further embodiment, Y=(CH₂)_(n), wherein n=1 to 2.

In another embodiment, the composition contains the following formulaand optionally salts thereof:

In another embodiment, the composition contains the following formula:

In another embodiment, the composition contains the following formula,where X— is a halide selected from chloride, bromide, iodide, andcombinations thereof and wherein Y=(CH₂)_(n), wherein n=1 to 8:

Various synthetic methodologies, which can be appreciated by one ofordinary skill in the art, can be utilized to make the claimedcompositions.

In one embodiment, a composition is produced by reacting an alkylacrylate with 1-methylpiperazine and then subsequently reacting theresulting product with an amine to form an amide and reacting said amidewith an alkyl halide.

In a further embodiment, the amine is oleylamine.

In a further embodiment, the alkyl halide is 1-bromohexane.

The compositions of this invention can contain one or more additionalchemistries. Various formulations can be appreciated by one of ordinaryskill in the art and can be made without undue experimentation.

In one embodiment, the composition further comprises one or more hydrateinhibitors.

In another embodiment, the composition further comprises one or morethermodynamic hydrate inhibitors, one or more kinetic hydrateinhibitors, one or more anti-agglomerants, or a combination thereof.

In another embodiment, the composition further comprises one or moreasphaltene inhibitors, paraffin inhibitors, corrosion inhibitors, scaleinhibitors, emulsifiers, water clarifiers, dispersants, emulsionbreakers, or a combination thereof.

In another embodiment, the composition further comprises one or morepolar or nonpolar solvents or a mixture thereof

In another embodiment, the composition further comprises one or moresolvents selected from isopropanol, methanol, ethanol, heavy aromaticnaptha, toluene, ethylene glycol, ethylene glycol monobutyl ether(EGMBE), diethylene glycol monoethyl ether, xylene, kerosene, diesel,isobutanol, heptane, or a combination thereof.

B. Methods

As stated above, the present invention provides for a method ofinhibiting the formation of hydrate agglomerates in a fluid comprisingwater, gas, and optionally liquid hydrocarbon comprising adding to thefluid an effective amount of a composition comprising the followingformula and optionally salts thereof:

where R₁ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; or H;where R₂ is a C₄ to C₂₂ alkyl;where R₃ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; or H;where R₄ is C_(n)H_(2n+1), wherein n=0 to 22; or Hwhere X⁻ is an anion, halogen, a carboxylate, or a sulfate and whereinX⁻ is only present when both R₁ and R₃ are present;where Y=(CH₂)_(n), wherein n=1 to 8; andwherein R₃ and R₁ can not be hydrogen or n=0 at the same time.

In one embodiment, the compositions contain various amounts of differentcompositions that fall within the claimed formula.

In another embodiment, the alkyl groups of R₁ and/or R₂ and/or R₄ arelinear, branched, cyclic, and/or unsaturated.

In another embodiment, R₃ is a methyl or ethyl group. When possible thealkyl groups can be linear or branched.

In another embodiment, the halogen is chlorine, bromine, or iodine. Thehalogen is in ionic form when it is associated with the composition.

In another embodiment, Y=(CH₂)_(n), wherein n=1 to 4. When possible, Yis linear or branched.

In another embodiment, R₁ is a C₄-C₈ alkyl.

In another embodiment, R₂ is a C₆-C₁₈ alkyl

In another embodiment, the composition contains the following formulaand optionally salts thereof:

where R₁ is C₄H₉, C₆H₁₃, C₈H₁₇, or benzyl;

where R₂ is a C₈H₁₇, C₁₂H₂₅, or C₁₈H₃₅;

where R₃ is CH₃ or C₂H₅;

where R₄ is C_(n)H_(2n+1), wherein n=0 to 22; or H

where X⁻ is an anion, halogen, a carboxylate, or a sulfate and whereinX⁻ is only present when both R₁ and R₃ are present;

where Y=(CH₂)_(n), wherein n=1 to 8; and

wherein R₃ and R₁ can not be hydrogen or n=0 at the same time.

In a further embodiment, Y=(CH₂)_(n), wherein n=1 to 2.

In another embodiment, the composition contains the following formulaand optionally salts thereof:

In another embodiment, the composition contains the following formula:

The composition is applied to a fluid that contains various levels ofsalinity.

In one embodiment, the fluid has a salinity of 1 to 20 weight/weight(w/w) total dissolved solids (TDS).

The composition is applied to a fluid that contains various levels ofwater cut. One of ordinary skill in the art would interpret water cut tomean the percentage (%) of water in a composition containing an oil andwater mixture.

In one embodiment, the water cut is from greater than 0% to 100%volume/volume (v/v).

In another embodiment, the water cut is from 1 to 60 volume/volume (v/v)percent.

Various synthetic methodologies, which can be appreciated by one ofordinary skill in the art, can be utilized to make the claimedcompositions. These compositions are then utilized in methods ofinhibiting the formation of hydrate agglomerates.

In one embodiment, a composition is produced by reacting an alkylacrylate with 1-methylpiperazine and then subsequently reacting theresulting product with an amine to form an amide and reacting said amidewith an alkyl halide.

In a further embodiment, the amine is oleylamine.

In a further embodiment, the alkyl halide is 1-bromohexane.

The compositions of this invention can contain one or more additionalchemistries. Various formulations can be appreciated by one of ordinaryskill in the art and can be made without undue experimentation.

In one embodiment, the composition further comprises one or more hydrateinhibitors.

In another embodiment, the composition further comprises one or morethermodynamic hydrate inhibitors, one or more kinetic hydrateinhibitors, one or more anti-agglomerants, or a combination thereof.

In another embodiment, the composition further comprises one or moreasphaltene inhibitors, paraffin inhibitors, corrosion inhibitors, scaleinhibitors, emulsifiers, water clarifiers, dispersants, emulsionbreakers, or a combination thereof.

In another embodiment, the composition further comprises one or morepolar or nonpolar solvents or a mixture thereof.

In another embodiment, the composition further comprises one or moresolvents selected isopropanol, methanol, ethanol, heavy aromatic naptha,toluene, ethylene glycol, ethylene glycol monobutyl ether (EGMBE),diethylene glycol monoethyl ether, xylene, kerosene, diesel, isobutanol,heptane, or a combination thereof.

The fluid in which the compositions and/or formulations are applied tocan be contained in many different types of apparatuses, especiallythose that transport a fluid from one point to another point, e.g. inone embodiment, the fluid is contained in an oil and/or gas pipeline.

In another embodiment, the fluid is contained in refineries, e.g.separation vessels, dehydration units, gas lines, and pipelines.

The compositions of the present disclosure and/or formulations thereofcan be applied to a fluid in various ways that would be appreciated byof ordinary skill in the art. One of ordinary skill in the art wouldappreciate these techniques and the various locations to which thecompositions or chemistries can be applied.

In one embodiment, the compositions and/or formulations are pumped intothe oil/gas pipeline by using an umbilical line. In a furtherembodiment, capillary injection systems can be utilized to deliver thesurfactants, in this case anti-agglomerants. U.S. Pat. No. 7,311,144provides a description of an apparatus and methods relating to capillaryinjection, which is herein incorporated by reference.

Various dosage amounts of a composition and/or formulation can beapplied to the fluid to inhibit the formation of hydrate agglomerates.One of ordinary skill in the art would be able to calculate the amountof anti-agglomerant for a given situation, e.g. content of aqueousmedium could be a factor, without undue experimentation.

In one embodiment, the dose range for the anti-agglomerant that isapplied to an aqueous medium, e.g. aqueous medium contained in anoil/gas pipeline, is between 0.1% volume to 2% volume based on watercut.

The methodologies described in the present invention may be utilizedwith other compositions that are commensurate in scope with thisapplication's disclosure. Other chemistries used for inhibiting theformation of agglomerants in fluids, which are outside the specificgeneric formula described above, but are commensurate in scope with theclaimed compositions generic formula, may be utilized if the systemconditions permit the compositions to inhibit the formation ofagglomerants (hydrate agglomerates); this protocol can be achievedwithout undue experimentation, specifically, e.g. the rocking testdescribed below can be utilized in determining whether a chemistry worksor not.

EXAMPLES I. Synthesis of Compositions/AA Chemicals GeneralProcedure/Scheme

The present invention relates to the synthesis and use of beta-aminoamide surfactants as anti-agglomeration chemicals. These surfactantspresent piperazine groups as the hydrophilic portion of the molecule anda fatty alkyl group as hydrophobes. Scheme 1 shows the generic syntheticprocedure for the preparation for the beta-amino amide compounds. Thefirst step of the reaction involves a Michael Addition reaction betweenan N-alkyl piperazine and methyl acrylate to make compound I (StructureI). Then compound I is reacted with an alkyl amine to form the amideadduct II (Structure II) and releases methanol as a by-product. The laststep of the synthesis requires the reaction of an alkyl halide withcompound II to form surfactant III (Structure III).

Representative Synthetic Procedure A. Synthesis of methyl3-(4-methylpiperazin-1-yl)propanoate

In a 500-mL 3-neck round bottom flask, 150.0 g (1.7 moles) of methylacrylate is charged. The reactor is cooled to 0° C. using an ice bath.Then, 77.0 g (0.77 moles) of 1-methyl piperazine are added slowly toprevent overheating of the reaction mass. The temperature should bemaintained below 50° C. by controlling the addition rate of 1-methylpiperazine. Overheating may cause polymerization of the excess methylacrylate present in the reactor. Once the addition is completed, themixture is agitated using a magnetic stirring bar and the temperatureadjusted to 50° C. for at least 16 hours. Then, the reaction is allowedto cool to ambient temperature and the excess methyl acrylate is removedunder vacuum. The final product is a light brown liquid at ambienttemperature. The transformation is monitored with thin layerchromatography (TLC) using 9:1 CHCl₃/MeOH. Complete conversion isapparent from the lack of olefinic protons in the ¹H-NMR spectra. ¹H-NMR(300 MHz, CDCl₃): δ 3.20 (s, 3H), 2.12 (t, 7.3 Hz, 2H), 1.94 (m, 10H),1.71 (s, 3H). ¹³C-NMR (75 MHz, CDCl₃): δ 171.31, 54.00, 52.41, 51.78,50.22, 44.92, 30.96.

B. Synthesis of N-dodecyl-3-(4-methylpiperazin-1-yl)propanamide

Methyl 3-(4-methylpiperazin-1-yl)propanoate 40.0 g (0.21 moles) anddodecylamine 39.7 g (0.21 moles) are charged into a 3-neck 250-mL roundbottom flask equipped with a Dean-Stark trap, thermocouple, and refluxcondenser. The mixture is agitated using a magnetic stirring bar andheated to 185° C. for five hours. The volume of methanol that isdistilled from the reaction is used to monitor the progress of thereaction. Evidence of the chemical transformation is observed by thinlayer chromatography (TLC) analysis using a 4:1 CHCl₃/MeOH as mobilephase. The final product is a light yellow solid at ambient temperature.¹H-NMR (300 MHz, CDCl₃): δ 2.98 (m, 2H), 2.07 (m, 1511), 1.27 (m, 2H),1.0 (m, 18H), 0.65 (t, 6.7 Hz, 3H). ¹³C-NMR (75 MHz, CDCl₃): δ 171.70,54.60, 54.39, 54.34, 53.45, 51.86, 45.39, 38.45, 31.60, 31.38, 29.14,29.11, 28.93, 28.85, 28.83, 26.65, 22.15, 13.61.

C. Synthesis of4-(3-(dodecylamino)-3-oxopropyl)-1-hexyl-1-methylpiperazin-1-ium bromide

N-dodecyl-3-(4-methylpiperazin-1-yl)propanamide 30.0 g (0.088 moles),1-bromohexane 14.6 g (0.088 moles), and 11.2 g of isopropyl alcohol arecharged into a 3-neck 250-mL round bottom flask equipped with athermocouple, and reflux condenser. The mixture is agitated using amagnetic stirring bar and heated to reflux overnight. Then, the reactionmass is cooled down to about 40° C. and diluted to 40% active solidswith 56 g of methanol. Evidence of the chemical transformation isobserved by TLC analysis using a 4:1 CHCl₃/MeOH as mobile phase. Thefinal product is a light brown solution at ambient temperature. ¹H-NMR(300 MHz, CDCl₃): δ 3.10 (m, 5H), 2.90 (m, 10H), 2.36 (in, 4H), 1.34(bs, 2H), 0.80 (in, 26H), 0.44 (m, 6H). ¹³C-NMR (75 MHz, CDCl₃): δ170.94, 62.39, 59.24, 52.17, 48.35, 45.12, 38.39, 32.50, 30.75, 30.12,28.52, 28.49, 28.38, 28.18, 28.18, 25.98, 24.85, 24.11, 21.50, 21.28,20.74, 12.92, 12.74.

D. Testing Samples

TABLE 1 Sample description Example R₂ R₁ R₃ X Blank N/A N/A N/A N/AComparative N/A N/A N/A N/A Example A Comparative N/A N/A N/A N/AExample B 1 —C₈H₁₇ None —CH₃ None 2 —C₁₂H₂₅ None —CH₃ None 3—(CH₂)₈CH═CH(CH₂)₈—H None —CH₃ None [cis isomer] 4 —CH(CH₃)(CH₂)₅—H None—CH₃ None 5 —CH₂CH(CH₂CH₃)(CH₂)₄—H None —CH₃ None 6 —C₈H₁₇ Benzyl —CH₃Cl 7 —C₁₂H₂₅ Benzyl —CH₃ Cl 8 —(CH₂)₈CH═CH(CH₂)₈—H Benzyl —CH₃ Cl [cisisomer] 9 —CH(CH₃)(CH₂)₅—H Benzyl —CH₃ Cl 10 —CH₂CH(CH₂CH₃)(CH₂)₄—HBenzyl —CH₃ Cl 11 —C₈H₁₇ n-Butyl —CH₃ Br 12 —C₁₂H₂₅ n-Butyl —CH₃ Br 13—(CH₂)₈CH═CH(CH₂)₈—H n-Butyl —CH₃ Br [cis isomer] 14 —CH(CH₃)(CH₂)₅—Hn-Butyl —CH₃ Br 15 —CH₂CH(CH₂CH₃)(CH₂)₄—H n-Butyl —CH₃ Br 16 —C₈H₁₇n-Hexyl —CH₃ Br 17 —C₁₂H₂₅ n-Hexyl —CH₃ Br 18 —(CH₂)₈CH═CH(CH₂)₈—Hn-Hexyl —CH₃ Br [cis isomer] 19 —CH(CH₃)(CH₂)₅—H n-Hexyl —CH₃ Br 20—CH₂CH(CH₂CH₃)(CH₂)₄—H n-Hexyl —CH₃ Br

II. Anti-agglomerate (AA) Testing A. Rocking Cell Procedure forAnti-Agglomeration Testing on Magnolia Crude Oil

A rocking cell has two parts, a manifold and a cell body. The manifoldis made up of stainless steel fittings that are welded together. It hasthree stems. An inlet stem is used to charge gas into the cell. Anoutlet stem is used to release the gas out of the cell. The third stemconnects to a transducer, which measures the pressure inside of thecell. The cell body has three layers. The outer layer is a polycarbonatetube, with a thickness that is 0.7 cm. The middle layer is made of astainless steel metal and is connected to the manifold. The inner layercontains a high-pressure sapphire tube, which has an outer diameter of2.8 cm, an inner diameter that of 1.85 cm, and a length of 5 cm. Thissapphire tube can handle pressure up to 3000 psi. A stainless steelball, which of 1.6 cm diameter is located inside a sapphire tube toinduce turbulence and mix the fluids during the rocking process.

The fluid usually contains three different components. For thisAnti-Agglomerate test, 7.2 mL of warm magnolia crude oil is firstinjected into the cell. Next, 4.8 mL of a solution containing 7% byweight of NaCl in DI water was injected into the cell to make a 40%water cut mixture. AA chemicals are then put into the cell. The dosageof the AA chemical is based on the amount of aqueous phase. The initialcondition for the test had a temperature of 21° C. Each cell is chargedby Green Canyon gas and pressurized up to 2500 psi. The cells wererocked for at least 1.5 to 2 hours until the fluid was saturated and thepressure became stable; then the temperature was set at 4° C. Therocking sequence was the following: cells were rocked for 16 hours(simulating steady state flowing); stayed static for 6 hours; and thenrocked back for 2 hours. Pressure data was recorded during this time.Observations were taken every two or three hours before the rocking wasstopped and right after the start up of the rocking test.

The AAs utilized above were diluted in methanol to a final concentrationof 60% actives. The only exception is comparative example B that has aconcentration of 40% actives in methanol. The solutions are then dosedto obtain a final concentration of 0.6% vol. of AA (based upon actives)in the aqueous phase. For example, a typical experiment at 40% water cutand a total volume of 12 mL will require 4.8 mL of brine, 7.2 mL of oil,and 29 μL of surfactant solution. The mixture is charged into therocking cell, as described above, and a stainless steel ball is added topromote mixing during the rocking part of the experiment.

The performance of the hydrate inhibitor is ranked from 1 (the worstperformer) to 5 (the best) based on the following criteria:

LDHI Rating System

Rating Test result Observations 1 Fail The rolling ball is stuck and/orthe liquid level has dropped below an observable amount. 2 Fail Large tomedium agglomerates are present and/or the liquid level has droppedsignificantly. There is significant resistance to the rolling of theball in the cell. 3 Marginal pass Medium agglomerates are formed in theviewable area and/or the liquid level has dropped moderately. There issome resistance to the rolling ball in the cell. 4 Pass Smallagglomerates are formed and/or the liquid level has dropped slightly,but the solution is free flowing without hindrance. 5 Pass Tiny andwell-dispersed hydrates in the hydrocarbon phase, high liquid level, andfree-flowing without hinderance.

B. Anti-Agglomeration Results

The function of AA chemicals is to disperse hydrate particles in the oilphase while preventing them from coagulating and causing plugs. Sincethe hydrates are dispersed in the oil phase, as the water cut increasesit becomes more difficult to achieve anti-agglomeration performance.

The AAs are diluted in methanol to a final concentration of either 40%or 60% actives. The solutions are then dosed to obtain a finalconcentration of 0.6% vol. of AA (based upon actives) in the aqueousphase. For example, a typical experiment at 40% water cut and a totalvolume of 12 mL will require 4.8 mL of brine, 7.2 mL of oil, and 29 μLof surfactant (AA containing) solution. The mixture is charged into therocking cell and a stainless steel ball is then added to promote mixingduring the rocking part of the experiment. Then, the cells are placedinside a temperature-controlled tank at 21° C. and pressurized to 2500psi with methane gas. The temperature of the rocking cell tank isgradually adjusted to 4° C. while rocking. The cells are rocked for 16hours (simulating steady-state flowing) followed by a 6-hour shut-in,then 2 more hours of rocking.

Table 2 below shows water cut data. Examples 1 to 5 are non-quaternarysurfactants of Structure II that contain different alkyl amides as thehydrophobic group. These materials are the intermediates for thepreparation of the quaternary ammonium surfactants of Structure III.They were evaluated for anti-agglomeration performance and only example3, which contains an oleyl amide group, demonstrated anti-agglomerationperformance at 40% water cut. Examples 6 to 10 are the benzyl quaternaryammonium salts series of surfactants. Evaluation of these surfactants inthe rocking cells demonstrated that they are not effective in preventinghydrate agglomeration at 40% water cut.

The n-butyl quaternary ammonium salts depicted in examples 11 and 13were effective anti-agglomeration chemicals. They showed goodperformance at water cuts up to 45%. These two examples are composed ofn-octyl and oleyl amides as the hydrophobic group, respectively.Surprisingly, example 12, which contains n-dodecyl amide group, failedat 40% water cut. This result is unexpected as based on priorexperiences; surfactants containing n-dodecyl groups tend to be moreeffective than when shorter hydrophobic groups are used. However, theresults from this single experiment do not necessarily mean an absolutefailure because other system conditions may result in a pass forcurrently failed experiments, e.g. lower water cuts, different brines,different gas compositions, other crude oils.

In general, the best anti-agglomeration performance is observed for thesurfactants in examples 16 to 20. These compounds present n-hexyl groupsas the R₂ group and different alkyl amides. The most effective AA isshown in example 18 where oleyl amide is the hydrophobic group of thesurfactant. This compound is effective in preventing the agglomerationof gas hydrates at water cuts as high as 60% in rocking cellexperiments. Another great performer is observed in example 17 where theR₁ group is n-dodecyl group. This surfactant provides hydrateagglomeration inhibition at water cuts up to 55%. Example 16, whichpresents an n-octyl amide group, also demonstrated good performance bypassing the AA test at 45% water cut. In summary, the optimum AAperformance is observed for the series of surfactants containing then-hexyl group in the R₂ position. Failures do not necessarily mean anabsolute failure because other system conditions may result in a passfor currently failed experiments.

TABLE 2 Anti-Agglomeration Results Maximum Example % Active ingredientDose % Water Cut Blank N/A N/A None Comparative Example A 60 1.0 40%Comparative Example B 40 1.5 40% 1 60 1.0 <40% 2 60 1.0 <40% 3 60 1.040% 4 40 1.5 Not tested yet 5 40 1.5 Not tested yet 6 60 1.0 <40% 7 601.0 <40% 8 60 1.0 <40% 9 40 1.5 Not tested yet 10 40 1.5 <40% 11 60 1.045% 12 60 1.0 <40% 13 60 1.0 45% 14 40 1.5 45% 15 40 1.5 40% 16 60 1.045% 17 60 1.0 55% 18 60 1.0 60% 19 40 1.5 <40% 20 40 1.5 45%

The invention is claimed as:
 1. A composition comprising the followingformula and optionally salts thereof:

wherein R₁ is selected from benzyl and linear, branched, and/or cyclicC₄H₉, C₆H₁₃, C₈H₁₇, and combinations thereof; wherein R₂ is a C₈H₁₇,C₁₂H₂₅, or C₁₈H₃₅; wherein R₃ is CH₃ or C₂H₅; wherein R₄ isC_(n)H_(2n+1), wherein n=0 to 22; or H wherein X⁻ is an anion, halide, acarboxylate, or a sulfate and wherein X⁻ is only present when both R₁and R₃ are present; and wherein Y=(CH₂)_(n), wherein n=1 to
 8. 2. Thecomposition of claim 1, wherein the halogen is selected from chloride,bromide, iodide, and combinations thereof.
 3. The composition of claim1, wherein Y=(CH₂)_(n), wherein n=1 to
 4. 4. The composition of claim 1,where Y=(CH₂)_(n), wherein n=1 to
 2. 5. The composition of claim 1,wherein the composition further comprises one or more hydrateinhibitors.
 6. The composition of claim 1, wherein the compositionfurther comprises one or more thermodynamic hydrate inhibitors, one ormore kinetic hydrate inhibitors, one or more anti-agglomerates, or acombination thereof.
 7. The composition of claim 1, wherein thecomposition further comprises one or more asphaltene inhibitors,paraffin inhibitors, corrosion inhibitors, scale inhibitors,emulsifiers, water clarifiers, dispersants, emulsion breakers, or acombination thereof.
 8. The composition of claim 1, wherein thecomposition further comprises one or more polar or nonpolar solvents ora mixture thereof.
 9. The composition of claim 1, wherein thecomposition further comprises one or more solvents selected fromisopropanol, methanol, ethanol, heavy aromatic naptha, toluene, ethyleneglycol, ethylene glycol monobutyl ether (EGMBE), diethylene glycolmonoethyl ether, xylene, kerosene, diesel, isobutanol, heptane, or acombination thereof.
 10. A composition comprising the following formulaand optionally salts thereof, wherein Y=(CH₂)_(n), wherein n=1 to 8:


11. The composition of claim 10, wherein Y=(CH₂)_(n), wherein n=1 to 4.12. The composition of claim 10, where Y=(CH₂)_(n), wherein n=1 to 2.13. A composition comprising the following formula, wherein X— is ahalide selected from chloride, bromide, iodide, and combinations thereofand wherein Y=(CH₂)_(n), wherein n=1 to 8:


14. The composition of claim 13, wherein Y=(CH₂)_(n), wherein n=1 to 4.15. The composition of claim 13, where Y=(CH₂)_(n), wherein n=1 to 2.16. The composition of claim 13, wherein X— is bromide.